Differences in the protein composition of fast- and slow-twitch muscle may be maintained by different rates of protein turnover. We investigated protein turnover rates in slow-twitch soleus and fast-twitch plantaris of male Wistar rats (body weight 412 ± 69 g). Animals were assigned to four groups (n = 3, in each), including a control group (0 d) and three groups that received deuterium oxide (D₂O) for either 10 days, 20 days or 30 days. D₂O administration was initiated by an intraperitoneal injection of 20 μL of 99% D₂O-saline per g body weight, and maintained by provision of 4% (v/v) D₂O in the drinking water available ad libitum. Soluble proteins from harvested muscles were analysed by liquid chromatography–tandem mass spectrometry and identified against the SwissProt database. The enrichment of D₂O and rate constant (k) of protein synthesis was calculated from the abundance of peptide mass isotopomers. The fractional synthesis rate (FSR) of 44 proteins in soleus and 34 proteins in plantaris spanned from 0.58%/day (CO1A1: Collagen alpha-1 chain) to 5.40%/day NDRG2 (N-myc downstream-regulated gene 2 protein). Eight out of 18 proteins identified in both muscles had a different FSR in soleus than in plantaris (p < 0.05).

During high-intensity (HI) exercise, metabolic acidosis significantly impairs exercise performance. Increasing the body's buffering capacity through training and exogenous intake of alkalizing supplements may improve high-intensity performance. Manipulating water and diet intake may influence the acid-base balance. The aim of this study was to determine the effects of mineral water rich in bicarbonate ions (STY) or placebo water (PLA) on circulating biomarkers and anaerobic performance and to verify whether alkalizing (ALK) or acidizing (ACI) diet would modulate these effects. Twenty-four athletes, assigned either to ALK (n = 12) or ACI (n = 12) diet for four weeks, completed a 1-min rowing Wingate Test in a double-blind and randomized trial after one week of daily hydration (1.5 to 2L/d) with either STY or PLA. Blood samples were taken before and after each test, and urine samples were collected each week. Chronic consumption of bicarbonate-rich water significantly impacted resting urinary pH irrespective of alkalizing or acidizing dietary intake. STY induced a significant increase in blood pH, lactate, and HCO3- ion concentration post-exercise compared to PLA. Similar changes were observed when STY was associated with the ALK diet. In contrast, STY combined with the ACI diet only significantly affected urine pH and peak blood lactate compared to PLA (p < 0.05). No effect of bicarbonate-rich water was reported on anaerobic performance (p > 0.05). Our results suggest that consumption of bicarbonate-rich water alters acid-base balance during a warm-up and after HI exercise, could potentiate beneficial effects of an alkalizing diet on the acid-base balance after HI exercise, and reduces the acid load induced by an acidifying diet.

The field of exercise physiology has undergone significant technological advancements since the pioneering works of exercise physiologists in the early to mid‐20th century. Historically, the ability to detect metabolites in biofluids from exercising participants was limited to single‐metabolite analyses. However, the rise of metabolomics, a discipline focused on the comprehensive analysis of metabolites within a biological system, has facilitated a more intricate understanding of metabolic pathways and networks in exercise. This review explores some of the pivotal technological and bioinformatic advancements that have propelled metabolomics to the forefront of exercise physiology research. Metabolomics offers a unique ‘fingerprint’ of cellular activity, offering a broader spectrum than traditional single‐metabolite assays. Techniques, including mass spectrometry and nuclear magnetic resonance spectroscopy, have significantly improved the speed and sensitivity of metabolite analysis. Nonetheless, challenges persist, including study design and data interpretation issues. This review aims to serve as a guide for exercise physiologists to facilitate better research design, data analysis and interpretation within metabolomics. The potential of metabolomics in bridging the gap between genotype and phenotype is emphasised, underscoring the critical importance of careful study design and the selection of appropriate metabolomics techniques. Furthermore, the paper highlights the need to deeply understand the broader scientific context to discern meaningful metabolic changes. The emerging field of fluxomics, which seeks to quantify metabolic reaction rates, is also introduced as a promising avenue for future research.

Purpose: The aim of this case study was to investigate whether the variation in parasympathetic branch activity, in conjunction with subjective data, could optimize the training prescription for an elite athlete during an Olympic season. Methods: During the preparatory phase for the Tokyo Olympic Games, a world-class female 3000m steeplechase runner (Age: 20 years, Height: 168 cm, Weight: 52 kg, VO2max: 67.1 mL⋅min⋅kg-1) recorded Heart Rate Variability (HRV), conducted orthostatic tests, and completed subjective evaluations four times a week throughout the different training periods that constitute a pre-Olympic season. The Pearson correlation coefficient and the Shapiro-Wilk test, along with paired T-tests, were used to assess correlations and compare mean differences between variables concerning baseline measurements and each of the other training periods. Results: The natural logarithm of the root mean square of the standard deviation during supine measurement (LnRMSSDsu) exhibited a significant negative correlation with the training load based on Rating of Perceived Exertion (RPE) and sleep quality (P < 0.05). Heart rate during supine measurement (HRsu) showed a significant positive correlation with subjective perceived exertion, sleep quality, stress, muscle soreness, and fatigue (P < 0.01). Compared to the baseline (rest), LnRMSSDsu, HRsu, RPE, and sleep quality were significantly different during the training, camp, and altitude training camp periods. Conversely, markers of standing Heart Rate Variability (HRV) did not differ during competition periods. Conclusion: Standing Heart Rate Variability, when combined with subjective markers, serves as a relevant monitoring tool for adapting training periods to regulate psychophysiological effects.

This review summarizes recent insights into the roles of the circadian clock in regulating cancer hallmarks, with a focus on its impact on the tumor microenvironment, and highlights the translational promise of circadian-informed strategies for cancer therapy. The circadian clock is a 24-hour biological timekeeping system that aligns physiological processes with cyclic environmental cues, such as light-dark cycles. Disruptions of circadian rhythms caused by lifestyle factors, including shift work, irregular sleep patterns, and jet lag, can lead to physiological dysregulation and increased risk of various diseases including cancer, positioning the circadian clock as both a critical driver of tumorigenesis and a potential target for chronotherapies. This review provides a comprehensive overview of circadian regulation in tumorigenesis across diverse cancer types by framing its role according to established cancer hallmarks, with particular emphasis on how the circadian system shapes immune cell dynamics within the tumor microenvironment to modulate tumor progression and immune surveillance. We further discuss recent preclinical and clinical advances in chronotherapy, highlighting how aligning therapeutic interventions with biological rhythms can enhance treatment efficacy, including responses to immunotherapy. By integrating mechanistic insights with translational applications, this review bridges circadian biology and oncology, providing a framework for future chronobiology-based cancer therapies.

High dietary carbohydrate (CHO) intake and reduced exercise training are recommended to optimize muscle glycogen stores pre‐endurance sports competition. However, the optimal CHO intake to support muscle glycogen synthesis and the dose–response of this relationship are still unknown in athletes who continue training pre‐competition. This study investigated the effects of different CHO intakes on muscle glycogen concentration. In a counterbalanced repeated measures design, 11 endurance‐trained participants (3 females, 8 males; age, 24 ± 5 years; body mass, 71.2 ± 12.0 kg; V̇ O _2max , 56 ± 6 mL kg ⁻¹ min ⁻¹ ) undertook 3 × 5 days of exercise and dietary control. During the final 48 h, participants ingested 6, 8 or 10 g kg ⁻¹ day ⁻¹ CHO prior to the assessment of muscle glycogen, gastrointestinal (GI) comfort and body composition. Muscle glycogen concentration was significantly higher following 10 vs. 6 and 8 g kg ⁻¹ day ⁻¹ (635.5 ± 78.0 vs. 460.9 ± 100.7 and 506.1 ± 124.0 mmol kg ⁻¹ dry mass, respectively, p < 0.03), with no difference between 6 and 8 g kg ⁻¹ day ⁻¹ ( p = 1.00). There was a strong positive correlation between relative CHO intake ( r = 0.71, p < 0.001) and skeletal muscle glycogen concentration. There was no effect of CHO intake on body mass ( p = 0.70) or GI symptoms ( p > 0.05), except fullness. In conclusion, there was a linear dose–response between dietary CHO intake and muscle glycogen in a protocol mimicking real‐world training and nutrition practices, as 10 g kg ⁻¹ day ⁻¹ achieved the highest muscle glycogen concentrations, with no detectable effect on body mass or GI symptoms, except increased fullness.